Debt Debt (Maximum Leverage Ratio) (Details)	3 Months Ended						9 Months Ended	12 Months Ended
	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Apr. 30, 2017	Jul. 31, 2017
current leverage ratio								746.00%
Required Total Leverage Ratio								550.00%
Debt Instrument, Covenant Compliance								67.5
Debt Instrument, Covenant Description								8.7
Ferrellgas, L.P. [Member]
current leverage ratio								746.00%
Required Total Leverage Ratio						550.00%
Debt Instrument, Covenant Compliance								67.5
Debt Instrument, Covenant Description								8.7
Maximum [Member]
Required Total Leverage Ratio	550.00%	775.00%	775.00%	775.00%	775.00%		550.00%
Maximum [Member] | Ferrellgas, L.P. [Member]
Required Total Leverage Ratio	550.00%	775.00%	775.00%	775.00%	775.00%
Minimum [Member]
Required Total Leverage Ratio	550.00%	550.00%	595.00%	595.00%	605.00%
Minimum [Member] | Ferrellgas, L.P. [Member]
Required Total Leverage Ratio	550.00%	550.00%	595.00%	595.00%	605.00%